Introduction

[This text is taken from the Florida Geological Survey Open File Report No. 80.]

The Florida Platform lies on the south-central part of the North
American Plant, extending to the southeast from the North American
continent separating the Gulf of Mexico from the Atlantic Ocean. The
Florida Platform, as measured about the 300 foot (91 meter) isobath,
spans more than 350 miles (565 kilometers) at its greatest width and
extends southward more than 450 miles (725 kilometers) at its greatest
length. The modern Florida peninsula is the exposed part of the platform
and lies predominately east of the axis of the platform. Most of the
State of Florida lies on the Florida Platform; the western panhandle is
part of the Gulf Coastal Plain.

The basement rocks of the Florida Platform include Precambrian-Cambrian
igneous rocks, Ordovician-Devonian Sedimentary rocks, and
Triassic-Jurassic volcanic rocks (Arthur, 1988). Florida's igneous and
sedimentary foundation separated from what is now the African Plat when
the super-continent Pangea rifted apart in the Triassic (pre-Middle
Jurassic?) and sutured to the North American craton (Smith, 1982).

A thick sequence of mid-Jurassic to Holocence sediments (unlithified to
well lithified) lies unconformably upon the eroded surface of the
basement rocks. Carbonate sedimentation predominate from mid-Jurassic
until at least mid-Oligocene on most of the Florida platform. In
response to renewed uplift and erosion in the Appalachian highlands to
the north and sea-level fluctuations, siliciclastic sediments began to
encroach upon the carbonate-depositing environments of the Florida
Platform. Deposition of siliciclastic-bearing carbonates and
siliciclastic sediments predominated from mid-Oligocene to the Holocene
over much of the platform. Numerous disconformities that formed in
response to nondeposition and erosion resulting from sea-level
fluctuations occur within the stratigraphic section.

The oldest sediments exposed at the modern land surface are Middle
Eocene carbonates of the Avon Park Formation which crop out on the crest
of the Ocala Platform in west-central Florida. The pattern of exposures
of younger sediments is obvious on the geologic map. Much of the state
is blanketed by Pliocene to Holocene siliciclastic-bearing sediments
that were deposited in response to late Tertiary and Quaternary sea-level
fluctuations .

The characteristic landscape of Florida is relatively to extremely flat.
There are few large, natural exposures and limited smaller exposures
that geologists can investigate. The result is that geologists must rely
primarily on de-watered or dry pits and quarries for exposures and must
make use of subsurface data in studying the geology of Florida.
Subsurface data, in the form of well cuttings and cores, were utilized
extensively in the development of this map. Formational tops recognized
in the subsurface have been extrapolated to the surface where exposures
are limited.

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